1. The Ganga River Basin

Stretching over an area of about 861,400 sq km, the Ganga and its tributaries drain the states of Uttarakhand, Himachal Pradesh, Haryana, Uttar Pradesh, Bihar, West Bengal, Jharkhand, Chhattisgarh, Madhya Pradesh, and Rajasthan. Its large left hand tributaries are Sharda, Kali, Gomti, Ghagra, Gandak, Kosi, and Mahananda; while the right hand tributaries include, the Yamuna, Chambal, Sind, Betwa, Ken, Son, and Damodar. Thus, from the mighty Himalayas and the northern Peninsular India, the Ganga and its tributaries carry enormous quantity of water. These rivers, due to heavy rains in the rainy season and melting of

snow in the spring season, cause heavy floods in the middle and lower reaches of their catchments. Kosi (means cuise-Kosna) has often been called the “Sorrow of Bihar”. Its flood in July 2008 caused heavy loss to life and property.

The cloud burst on 16th June, 2013 in Uttarakhand resulted into disaster in which the sacred places such as Kedarnath Rambara, Joshimath were seriously damaged. Except the Kedarnath temple almost the entire settlement was hurried under sediments, boulders and coarse-sand.

The state of Uttar Pradesh alone constitutes about 22 per cent of the flood prone area of the country. The river channels of these rivers are increasingly getting shallower, especially in their middle and lower reaches. In the event of heavy rainfall, these rivers cross their banks and inundate the neighbouring khadar areas.

In Bihar, floods are largely confined to the northern part of the state where occurrence of flood is almost an annual feature during the season of general rains. The rivers like Burhi Gandak, Bagmati, Kosi, and the lower reaches of the Mahananda spill over their banks and inundate the low lying khadar areas. The Kosi flood 2009, created havoc in the districts Saharsa, Medhapur, and Khagaria of Bihar. Many of the cities and towns were submerged under water causing enromous loss to life and property.

In West Bengal, the southern and central parts are frequently flooded during the season of southwest monsoon. The Mahananda, Bhagirithi, Ajoy, and Damodar (Sorrow of Bengal) are often in floods in rainy season. Even after the formation of the Damodar Valley Corporation (DVC), there occur occasional floods in the rivers.